A liquid packaging container for medical use, such as an infusion solution bag, having been used is formed of glass or plastics. A medical solution charged in an infusion solution bag is sealed, and then sterilized generally by such a method as steam sterilization and autoclave sterilization. An infusion solution bag formed of glass has a problem of a larger weight thereof and a higher possibility of breakage due to impact, fall or the like during transportation, than a plastic bag, and thus an infusion solution bag formed of plastics has been widely used.
An infusion solution bag formed of plastics having been used is formed of a soft vinyl chloride resin or a polyolefin, such as polyethylene and polypropylene. An infusion solution bag formed of a soft vinyl chloride resin contains a large amount of a plasticizer for imparting flexibility thereto, and therefore there is a possibility depending on the kind of the infusion solution that the plasticizer is eluted into the infusion solution, which may bring about a concern in safety. Furthermore, an infusion solution bag formed of a soft vinyl chloride resin is incinerated after used since medical instruments are disposable, but there is a problem that a toxic gas derived from the soft vinyl chloride resin is generated. Moreover, an infusion solution bag formed of a polyolefin, such as polyethylene and polypropylene, is favorable from the standpoint of hygiene since no plasticizer is contained therein, but cannot be said to be sufficient in handleability due to the low flexibility and the insufficient impact resistance thereof.
For achieving the object of providing a resin composition providing a molded article that is excellent in flexibility and transparency and also providing a medical instrument that does not generate toxic gas on incineration, has sufficient heat resistance, and withstands autoclave sterilization, there is a proposal of a resin composition containing (a) a polypropylene resin, and at least one of (b) a hydrogenated block copolymer selected from the group consisting of (b-1) a hydrogenated block copolymer having one or more of a polymer block A formed of a vinyl aromatic compound, and one or more of a polyisoprene block B having a content of a 1,2-bond and a 3,4-bond of from 10 to 75% by mol, in which the content of the vinyl aromatic compound is from 10 to 40% by weight, and 70% or more of the carbon-carbon double bonds of the polyisoprene block B are hydrogenated, (b-2) a hydrogenated block copolymer containing one or more of a polymer block A formed of a vinyl aromatic compound, and one or more of a polymer block C formed of a polymer of a mixture containing isoprene and butadiene at a weight ratio of from 5/95 to 95/5, and having a content of a 1,2-bond and a 3,4-bond of from 20 to 85% by mol, in which the content of the vinyl aromatic compound is from 10 to 40% by weight, and 70% or more of the carbon-carbon double bonds of the polymer block C are hydrogenated, and (b-3) a hydrogenated block copolymer containing one or more of a polymer block A formed of a vinyl aromatic compound, and one or more of a polybutadiene bock D having a content of a 1,2-bond of 45% by mol or more, in which the content of the vinyl aromatic compound is from 10 to 40% by weight, and 70% or more of the carbon-carbon double bonds of the polybutadiene block D are hydrogenated, in which the ratio thereof (polypropylene resin (a))/(hydrogenated block copolymer (b)) is from 10/90 to 90/10 (weight ratio) (see PTL 1).
For achieving the object of providing a tube that is excellent in transparency, flexibility, kink resistance, agglutination resistance, forceps resistance, solvent adhesiveness, low temperature impact resistance, and heat resistance, there is a proposal of a tube formed by molding a resin composition containing a hydrogenated block copolymer (a), a hydrogenated block copolymer (b), and a polyolefin resin (c), in which the hydrogenated block copolymer (a) is a hydrogenated block copolymer obtained by hydrogenating a block copolymer constituted at least by a polymer block (A) formed mainly of an aromatic vinyl compound unit and a polymer block (B) formed mainly of a butadiene unit or formed mainly of an isoprene unit and a butadiene unit, the content of the polymer block (A) is from 5 to 40% by mass with respect to the total amount of the hydrogenated block copolymer (a), the hydrogenation ratio of the polymer block (B) is 70% or more, the copolymer has a glass transition temperature of from −45 to 30° C., the hydrogenated block copolymer (b) is a hydrogenated block copolymer obtained by hydrogenating a block copolymer constituted at least by a polymer block (C) formed mainly of an aromatic vinyl compound unit and a polymer block (D) formed mainly of a butadiene unit or formed mainly of an isoprene unit and a butadiene unit, the content of the polymer block (C) is from 10 to 40% by mass with respect to the total amount of the hydrogenated block copolymer (b), the hydrogenation ratio of the polymer block (D) is 80% or more, the copolymer has a glass transition temperature of less than −45° C., the mass ratio ((a)/(b)) of the hydrogenated block copolymer (a) and the hydrogenated block copolymer (b) is from 50/50 to 95/5, and the mass ratio ((c)/((a)+(b)+(c))) of the hydrogenated block copolymer (a), the hydrogenated block copolymer (b), and the polyolefin resin (c) is from 10/100 to 60/100 (see PTL 2).